Unmanned floating buoys are presently known in the art of sea reconnaissance. These buoys are equipped with suitable sensors such as sonars and are used for detecting the presence and movement of ships and submarines. The analysis of the signals received from the buoys allows determination of the type, speed and direction of the ship that has been detected. The use of data from several floating buoys increases the accuracy of the analysis.
Other known unmanned combat systems for deployment in the sea are sea mines, which are either anchored or allowed to float freely. These mines may be activated automatically through timers, or remotely, by way of radio link or ultra-sound. The mines may also be detonated either automatically or remotely. Automatic detonation is effected by suitable sensors such as contact-devices, magnetic detectors or acoustical detectors. An inherent disadvantage of ordinary sea mines is that they cannot positively identify a target before detonation. They accordingly represent a danger to friendly as well as enemy vessels.